Effective and safe adjuvants are used to make subunit vaccines and immunotherapies sufficiently immunogenic. Simple mixing of an adjuvant with subunit vaccines or with immunotherapies often requires adding quantities of adjuvant that may lead to unwanted side-effects. Such mixing may require highly demanding and costly process development and product characterization, lead to poor shelf-life duration, or result in an inability to freeze or lyophilize the final product. Moreover, adjuvant dosing requirements may lead to re-instatement of unwanted side-effects. Accordingly, there is a need to improve the effectiveness of adjuvanted subunit vaccines and immunotherapies.
For optimal antigen presentation to T cells, antigens and adjuvants must not only be taken up by the same antigen presenting cell, but they need to be taken up by the same phagosome (Medzhitov, Nature 2006, Vol. 440). Conventional antigen/adjuvant mixtures often require large amounts of adjuvant to ensure that both are phagocytosed simultaneously. Excess adjuvant leads to overt reactogenicity that limits the usefulness of such adjuvant systems.